Conveyor belts with long drive pitch

ABSTRACT

A conveyor comprising a modular belt constructed of rows of belt modules in which only alternate rows are engaged by the teeth of a drive sprocket. Alternate belt rows have drive recesses for receiving the sprocket teeth. The belt rows not engaged by the sprocket are devoid of drive pockets.

BACKGROUND

The invention relates generally to power-driven conveyors and inparticular to belt conveyors that have a drive pitch longer than thebelt's articulation pitch.

Modular conveyor belts are constructed of rows of belt modules linkedtogether at hinge joints. Conventionally, each belt row has one or moredrive surfaces engaged by drive faces—e.g., teeth on the peripheries ofsprockets. The spacing of consecutive hinge joints defines the beltpitch. The spacing of consecutive drive surfaces defines the belt'sdrive pitch. Usually the belt pitch and the drive pitch are equal. Forsmall-pitch belts driven on each row, the thickness of the teeth has tobe small. But, because thin teeth lack material, they are highly subjectto wear. As the thin teeth wear, they weaken and then fail.

SUMMARY

One version of a conveyor embodying features of the invention comprisesa conveyor belt constructed of first rows of first belt modules andsecond rows of second belt modules. The first rows and the second rowsare alternately connected to each other in series at hinge jointsbetween consecutive first and second rows. A sprocket has teeth thatengage the first rows of first belt modules and not the second rows ofsecond belt modules.

Another version of a conveyor embodying features of the inventioncomprises a conveyor belt constructed of a series of rows of beltmodules linked together at hinge joints between consecutive rows. Thehinge joints have hinge axes spaced apart in a direction of belt travelby a distance defining the belt pitch. A sprocket has teeth that engageevery other row of belt modules. The circumferential spacing of theteeth defines the drive pitch, which, in this case, is twice the beltpitch.

In another aspect a modular conveyor belt embodying features of theinvention comprises a plurality of first rows of first belt modules anda plurality of second rows of second belt modules. The first rows andthe second rows are alternately connected to each other at hinge jointsbetween consecutive first and second rows. Each of the first rows has adrive face for receiving a drive tooth, and all the second rows aredevoid of drive faces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an axonometric view of a portion of a conveyor embodying thefeatures of the invention;

FIG. 2 is a cutaway side view of the conveyor of FIG. 1 taken alonglines 2-2;

FIG. 3A is a top plan view of a belt module without drive pockets thatis used to construct a belt as in FIG. 1;

FIG. 3B is a bottom plan view of the belt module of FIG. 3A;

FIG. 4A is a top plan view of a belt module with a drive pocket forconstructing a belt as in FIG. 1;

FIG. 4B is a bottom plan view of the belt module of FIG. 4A;

FIG. 5 is an enlarged view of the underside of a belt module as in FIG.4B showing details of the drive pocket; and

FIG. 6 is a side elevation view of a portion of the belt of FIG. 1 goingaround a small-diameter nosebar.

DETAILED DESCRIPTION

A portion of a conveyor embodying features of the invention is shown inFIGS. 1 and 2. The conveyor 18 comprises a modular conveyor belt 12engaged by teeth 14 on the periphery of a sprocket 16. The sprocketshown is a drive sprocket rotated by a motor-driven shaft (not shown) ina clockwise direction of rotation 18 to advance the conveyor belt 12 ina direction of belt travel 20. The modular conveyor belt 12 isconstructed of a series of rows A, B of belt modules 22, 23. In thisversion each row is composed of a single belt module. But each row couldbe constructed of multiple side-by-side modules arranged with themodules in consecutive rows in a bricklay fashion. The A rows alternatewith the B rows. Consecutive rows are joined at hinge joints 24. Leadinglink ends 26 along each row interleave with trailing link ends 27 of aleading row. Holes 28 through the interleaved link ends 26, 27 arealigned to form a lateral passageway for a hinge rod 30 to connectconsecutive rows together at the hinge joints 24. The hinge joints 24define hinge axes 32 about which the modules 22, 23 articulate. Thedistance between consecutive hinge axes 32 is the belt pitch P.

The teeth 14 on the periphery of the sprocket 16 engage every other beltrow—in this case, belt row B. Belt row A is not engaged by the sprocketteeth 14. As shown in FIG. 2, the circumferential spacing of the teeth14 on the periphery of the sprocket defines the sprocket, or drive,pitch D. Because the teeth 14 engage only every other row, the drivepitch is twice the belt pitch P. This allows the thickness T of theteeth 14 to be greater than if they had to drive every belt row. Thethick teeth 14 are stronger and more durable than thin teeth.

The thicker teeth 14 intersect a portion of every other lateral hingerod passageway. So two hinge rods 30, 30′, each entering an oppositeside of the belt 12, extend laterally from the sides to positions justshort of the teeth to connect the rows together. As an alternative, asingle full-length hinge rod that extends all the way across the widthof the belt can be used if a recess 34 is formed in the tops of each ofthe teeth 14, as shown in FIG. 2 on one of the teeth. The lateral recess34 provides clearance for the full-length hinge rod.

As shown in FIG. 1, the A rows differ from the alternate B rows. Forexample, the side edges 36, 37 of the A rows are thickened and form themajority of the side edges of the belt 12. The B rows, on the otherhand, terminate at their side edges in small stubs 38 that fit into thespaces between the side edges 36, 37 of the A rows. The two sets of rowsA, B are shaped complementarily to provide the belt 12 with a closedconveying surface 40, except for the seams between adjacent beltmodules.

A single-module A row is shown in more detail in FIGS. 3A and 3B. TheA-row module 22 comprises two interior links 42 and two outer links44—the side-edge pieces 36, 37, of FIG. 1. The links 42, 44 terminate inthe leading and trailing link ends 26, 27. The links 42, 44 are spacedfrom each other by gaps 46. Narrow bridges 48 extend from the sides ofthe links 42, 44 laterally across the gaps 46 between the link ends 26,27. The tops of the bridges 48 and the tops of the links 42, 44 form theconveying surface 40 of the belt 12 as in FIG. 1. As seen from thebottom side of the A-row module 22 in FIG. 3B, the interior links 42 aredevoid of drive pockets that receive sprocket teeth. FIG. 3B also showsthat the bridges 48 are thin webs connected between consecutive links42, 44 without extending deeply into the gaps 46 toward the undersidesof the module 22.

A complementary single-module B row is shown in FIGS. 4A and 4B. Themodule 23 is shown with one interior link 50 and two outer links 52joined across gaps 47 by bridges 49. The edge stubs 38 extend laterallyoutward from the outer sides of the outer links 52. The stubs 38 areessentially extensions of the bridges 49. Like the bridges 48 in theA-row modules 22, the bridges 49 and stubs 38 in the B-row modules 23are thin and extend laterally across gaps 47 between consecutive links50, 52. As shown in FIG. 4B, the interior link 50 has a drive pocket 54recessed into its underside. The drive pocket 54 receives the sprocketteeth 14 (FIG. 2). As shown in FIG. 1 and is clear from FIGS. 3A and 4A,the A-row modules 22 interfit with the B-row modules 23 to form aclosed-area belt 12. The links 42, 44 of the A-row modules 22 arelaterally offset from the links 50, 52 of the B-row modules 23 so thattheir leading and trailing link ends 26, 27 fit in the gaps 46, 47 ofconsecutive rows. The interleaved link ends 26, 27 of consecutive rowsthen form the aligned passageways for the hinge rods. The A-row links42, 44 are arranged in longitudinal lanes of links separated by theB-row bridges 49. And the B-row links 50, 52 are similarly arranged inlongitudinal lanes of links separated by the A-row bridges 48.

Further details of the drive pocket 54 of the B-row link 50 are shown inFIG. 5. The drive pocket has an inner drive face 56 against which adrive-sprocket tooth pushes to move the belt in the forward direction58. When the direction of belt travel is reversed, the drive-sprockettooth engages an outer drive face 57 on the next consecutive B-rowmodule to move the belt in the reverse direction 59. The link end 27 hasboth drive faces: the inner drive face 56 bounding the drive pocket 54and the outer drive face 57 bounding the drive pocket of the nextconsecutive B-row link. The drive pocket 54 has three walls. The forward(or rearward) wall is formed by the inner drive face 56. Two parallelside walls 61, 63 extend from the forward wall 56 to flank thethree-sided pocket 54, which is closed on the fourth side by the outerdrive face 57 of the neighboring B-row link end.

As shown in FIG. 6, the bottoms 60, 62 of the B-row links 50, 52 and theA-row links 42, 44 are concavely scalloped to allow the conveyor belt toarticulate around a small-diameter nose bar 64 for tight producttransfers off the end of a belt run.

The belt modules described can be made of various materials, but wouldmost commonly be injection-molded out of a thermoplastic material. Thebelt modules can be made with a very small belt pitch, such as 8 mm orless.

Although the invention has been described in detail with reference to aspecific version, other versions are possible. For example, thenon-driven belt rows could have drive pockets that are not used forengagement with sprocket teeth. Alternatively, the drive pockets couldbe formed in the A rows and not the B rows, the A rows engaging thesprocket teeth instead. As another example, the drive faces could extenddownward from the undersides of the sprocket-engaging modules to form amale drive element on the belt rather than a female receptacle. In thatcase the sprocket would have a female recess engaging male drive faceson the belt.

What is claimed is:
 1. A conveyor comprising: a conveyor beltconstructed of a plurality of first rows of first belt modules and aplurality of second rows of second belt modules wherein the first rowsand the second rows extend across the width of the conveyor belt from afirst side edge to a second side edge and are alternately connected toeach other in series at hinge joints between consecutive first andsecond rows; a sprocket having teeth engaging the first rows of firstbelt modules and not the second rows of second belt modules.
 2. Aconveyor as in claim 1 wherein the first rows of first belt modulesengaged by the teeth of the sprocket have drive pockets receiving theteeth.
 3. A conveyor as in claim 2 wherein the second rows of secondbelt modules not engaged by the teeth of the sprocket are devoid ofdrive pockets.
 4. A modular conveyor belt comprising: a plurality offirst rows of first belt modules and a plurality of second rows ofsecond belt modules wherein the first rows and the second rows extendacross the width of the conveyor belt from a first side edge to a secondside edge and are alternately connected to each other at hinge jointsbetween consecutive first and second rows; wherein each of the firstrows has a drive face for receiving a drive tooth and wherein all thesecond rows are devoid of drive faces.
 5. A modular conveyor belt as inclaim 4 wherein the first rows of first belt modules and the second rowsof second belt modules each comprise: a plurality of links extending ina direction of belt travel from a first link end to a second link endand separated by gaps between facing sides of consecutive links; aplurality of bridges extending between facing sides of consecutive linksacross the gaps between the first link ends and the second link ends. 6.A modular conveyor belt as in claim 5 further comprising a drive pocketformed in one of the links in each of the first rows and bounded by thedrive face to receive a drive tooth.
 7. A modular conveyor belt as inclaim 6 wherein the drive pocket is bounded by the second link end ofthe link at one end of the drive pocket and by the second link end ofthe next consecutive link at the other end.
 8. A modular conveyor beltas in claim 5 wherein the links and the bridges form a closed conveyingsurface on each belt module in each row.
 9. A modular conveyor belt asin claim 5 wherein the bridges are equidistant from the first and secondlink ends.
 10. A conveyor comprising: a conveyor belt constructed of aseries of rows of belt modules linked together at hinge joints betweenconsecutive rows, wherein the hinge joints have hinge axes spaced apartin a direction of belt travel by a distance defining the belt pitch; asprocket having teeth engaging every other row of belt modules, whereinthe circumferential spacing of the teeth defines the drive pitch; andwherein the drive pitch is twice the belt pitch.
 11. A conveyor as inclaim 10 wherein every other row of belt modules includes at least onedrive face engaging the teeth of the sprocket.
 12. A conveyor as inclaim 10 wherein every other row of belt modules includes at least onedrive pocket receiving the teeth of the sprocket.
 13. A conveyor as inclaim 10 wherein the belt modules comprise: a plurality of linksextending in a direction of belt travel from a first link end to asecond link end and separated by gaps between facing outer sides ofconsecutive links across the width of the belt row; a plurality ofbridges extending between the facing outer sides of consecutive linksacross the gaps between the first link end and the second link end. 14.A conveyor as in claim 13 further comprising a drive pocket formed inone of the links in every other row and bounded by a drive face engagedby the teeth of the sprocket.
 15. A conveyor as in claim 13 wherein thelinks and the bridges form a closed conveying surface.